Wireless communications technology is rapidly evolving to address the ever-increasing need for additional bandwidth and services. With each generation of wireless communication standards, the available bandwidth and services that are made available to subscribers have dramatically increased. Unfortunately, each generation of wireless communication standards generally requires additional network infrastructure and compatible user elements. In many instances, the network infrastructure of a new generation does not support that of an earlier generation. Further, different networks and generations thereof handle voice and data in different ways. For example, second generation (2G) networks rely heavily on circuit-switched communications for voice and data, while many third generation (3G) networks provide circuit-switched subsystems as well as packet-based subsystems for voice and data, respectively. Upcoming fourth generation (4G) networks may use packet-based subsystems for voice and data with little or no reliance on a circuit-switched subsystem.
In many environments, different types of subsystems and different generations of networks are available to a user element. Many user elements are able to support services on these different subsystems and different generations of these subsystems. However, transitioning from a packet subsystem of one generation to a circuit-switched subsystem of another generation, and vice versa, has proven to be cumbersome. Accordingly, there is a need for technique to efficiently and effectively transition support of communication sessions for a user element between different types of subsystems of different generations in an effective and efficient manner.